The major objective of this proposal is to assess in postoperative patients the nutritional value and hormonal effects of various types of enteral and parenteral fluid regimens by measurement of specific protein synthesis. Prospective, randomized clinical trials of various combinations of glucose, amino acids and fat have been designed in which the effects of these solutions on albumin biosynthesis will be measured by the highly specialized (14C) carbonate method. Since this technique requires only a 12-hour period of steady state conditions, it can be adapted to patients with malignancy, and patients who are critically ill in an intensive care unit. The hypothesis that a positive nitrogen balance reflects a net gain of protein synthesis over protein catabolism will be tested by comparing conventional nitrogen balance data with albumin synthesis rate data and nitrogen balance estimates obtained from the difference between nitrogen intake and urea nitrogen synthesis rate, the latter of which is determined by the (14C) carbonate technique. Measurement of albumin synthesis rate in patients provides a highly specific tool to investigate how effectively parenterally or enterally administered solutions of glucose, amino acids and fat are utilized for purposes of protein synthesis, information which is not currently available, but which is urgently needed to place the role of these solutions in better nutritional perspective. In the course of these investigations, new information concerning the effect of various solutions on hormone interactions (insulin and glucagon) and on carbohydrate, protein and fat substrates will also be obtained.